Disorders of appetite are a serious problem of mental health. This research is designed to explore the biological foundations of ingestive behavior and develop and animal model for the study of neural mechanisms of motivation. The feeding and drinking behaviors of the pigeon exhibit the essential features of vertebrate ingestvie behavior but have a number of characteristics that make them amenable to experimental analysis at the cellular level. The present application proposes studies designed to delineate the central projections of the viscerosensory sytems conveying afference from the gastrointestinal systems; to indentify brain structures involved in the neural control of drinking behavior; to carry out analyses of the activity in oromotor structures during ingestive behavior and to develop a preparation for correlated physiological and behavioral studies of hunger and thirst. Experimental anatomical tracing procedures including HRP histochemistry and autoradiography are used to trace the viscerosensory pathways; 14C-2DG autoradiography is used in the study of thirst mechanisms; classical conditioning techniques will be used to elicit ingestive movements in immobilized subjects and electromyography will be employed to study activity in the jaw muscles.